/Engine/Plugins/Editor/GeometryMode/Source/GeometryMode/Public/GeometryEdMode.h
true if something was selected/deselected, false otherwise.
virtual bool FrustumSelect ( const [FConvexVolume](API\Runtime\Engine\FConvexVolume) & InFrustum, [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) * InViewportClient, bool InSelect )